I dont understand how to use this mod.

No worries!

Sorry mate i put it on the wrong mod its the gun seller that is showing any guns.

Not sure you're looking in the right place? The Character spawned in Chinatown is a man that's selling explosives.

the woman has no guns for sale for me?

Hi! The source code for the game is now included as a zip file in the Steam install folder. This page on the moding wiki explains where to find it:
https://eos.paradoxwikis.com/Modding_tips#Using_the_game_source_code_for_reference

Where is the itemid list? I used to found it in Empire of Sin\EmpireOfSin_Data\StreamingAssets\GameData_Win64~\Lua\Scripts\DataSheets
WeaponRanges.lua on previous version but it's not there anymore. it's look like you changed the files and not update your wiki page yet.

Please make it like Europa Universalis mod wiki pages (well, they make a mini internet on their pages, so just have 50% like it is good enough).

Great works btw, thank you!